[hanzmanner]

Delta tells me that there is a seat available at this price before I agree to it. After I agree to it it tells me that there is no seat available at this price unless I pay more.

The agreed upon "seat" in this context includes the selection. This is what this specific dark pattern is about. They are misrepresenting the value of their offering. I want to be able to reserve a seat on my flight. Not to reserve a promise that they will assign a seat... if available, obviously. If not I can just book the next flight and wait for a couple of hours at the ariport. Perfect.